By 2026, all new buildings and substantial renovations in D.C. will have to be net-zero construction, meaning they produce as much energy as they consume, under legislation passed unanimously by the D.C. Council. The legislation, which also bans most natural gas use in new buildings, has now been signed by Mayor Muriel Bowser.

Separate climate legislation, also signed by Bowser, commits to making the entire city carbon neutral by 2045.

“Buildings account for close to 75% of the District’s emissions,” said Councilmember Mary Cheh, who introduced the bills, during discussion of the legislation. “So making our buildings more efficient and ensuring that they use clean energy, is probably one of the most important steps we can take to achieve carbon neutrality.”

Building emissions come from the electricity and natural gas used for heating, air conditioning, hot water, cooking, and everything else that requires power. Earlier this year, a study found that ample natural gas leaks around the District are a contributor to climate change.

Mike Tidwell, executive director of the Chesapeake Climate Action Network, said the District had “raised the bar on climate action, not only in the nation’s capital, but for the whole country.”

“The District is now ahead of most states and most cities,” Tidwell said.

The clean building legislation, just four pages long, does not itself create the new net-zero building codes, but rather instructs the mayor to do so by no later than Dec. 31, 2026. Buildings will be prohibited from using “on-site fuel combustion” (aka, burning natural gas) for furnaces or water heaters. There is an exemption to the fuel combustion ban for backup power generators in “buildings that are essential to protecting public health and safety.”

The net-zero building codes will cover all commercial buildings, condo and apartment buildings, as well as single family homes taller than three stories.

The bill also requires audits every three years, starting in 2029, to report what percentage of new buildings are complying with the net-zero requirements.

Net-zero buildings are achieved through a combination of keeping energy demand low and producing clean energy. These buildings are highly insulated and airtight, which keeps them cool in the summer and warm in the winter, and use efficient electric heating and cooling systems. They produce as much or more energy than they need through renewable means, like solar panels.

“It’s a win for the climate, it’s a win for public health, and it’s a win in utility bill savings,” said Mark Rodeffer, with the D.C. chapter of the Sierra Club. “The only loser here is companies that make money by selling fossil fuels — everyone else wins.”

The Climate Commitment Act, which also passed unanimously, for the first time codifies in D.C. law the city’s greenhouse gas reduction goals. The bill also speeds up the timeframe for ditching fossil fuels, committing to going carbon neutral five years earlier than the previous goal of 2050. Shorter term goals in the legislation include a 60% cut in carbon emissions by 2030, and District government-owned buildings going carbon neutral by 2040.

Even sooner, by 2025, the D.C. government will have to stop installing natural-gas-powered furnaces and water heaters, instead using more efficient electric heat pumps, which can be powered by clean energy. By 2026, the District will have to stop purchasing gas-powered vehicles, instead buying zero-emission ones.

“We’re taking a very pragmatic approach,” said Cheh. “We aren’t requiring the District to tear out old gas boilers or sell off its entire fleet of gas-powered vehicles. We’re allowing for it as we go forward, and in cases where there are issues, there will be flexibility.”

The bills will become law after a 30-day congressional review period.

This story was updated after Mayor Bowser signed the legislation.